The present invention relates to bicycle wheel mount assemblies and, more specifically, to a bicycle dropout assembly that allows splitting of the chain and seat stays without altering a relation of an axle relative to a bicycle and that provides for tensioning of the drive system in a convenient manner.
Commonly, the front and rear tires of a bicycle are supported by respective drop out assemblies that provide the connection between a skewer, axle or hub of a wheel assembly and the frame of the bicycle. With respect to the rear wheel assembly, a flexible or endless drive, such as a belt or chain, extends between a crankset associated with the pedals, and a gear set that is drivingly associated with the rear wheel. Those skilled in the art will appreciate the structural and vernacular distinctions with respect to bicycle drive systems equipped with a belt as compared to those equipped with a chain. That is, it is appreciated that many belt driven drive system are equipped with pulleys and/or splined drive members as compared to the many toothed gears associated with chain driven systems.
As used herein, a drive member of the drive train is that portion of the bicycle drive system that is connected to, and directly driven by, the bicycle pedals. A flexible drive or flexible drive member, such as a chain or belt, is operatively associated with the drive member and communicates a drive force to a driven member. The driven member is operatively associated with a wheel assembly so that rotation of the driven member rotates the wheel assembly. Either or both of the drive and driven member may include more than one drive surface whose interaction with the flexible drive member alters the gearing of the drive train.
Regardless of the type of flexible drive associated with the drive system, the endless drive must be appropriately adjusted so as to maintain a desired operational interaction between the respective drive and driven members of the drive system and the endless drive member. Commonly, with chain and belt systems, the endless drive is adjusted or “tensioned” by adjusting the position of the rear wheel axle relative to an axis of rotation of the drive member or crankset. Operation of a screw or other adjuster, commonly referred to as a tensioner system, linearly translates the axle relative to the crankset until a desired orientation of the drive system is achieved. Although such systems are generally simple to operate, such systems are not without their respective drawbacks.
Such tensioner systems commonly include a screw or other rotatable operator, a backing plate against which the operator translates, and a slide that interacts with the axle and alters a position of the axle relative to the frame in response to manipulation of the operator. Although such systems are generally simple to operate, they tend to complicate the manufacture of the bicycle and detrimentally increase the overall weight of the bicycle.
Such wheel mounting systems also suffer from an additional drawback related to wheel service. Commonly, if the wheel needs to be removed for service, such as for replacing a tire or the like, the tensioning system is adjusted to allow the hub to be disengaged from the bicycle. Even though the tensioning system is adjusted to remove the wheel assembly from the bicycle, after servicing the wheel, the wheel is generally returned to the same position with respect to the bicycle. Accordingly, servicing of the wheel commonly requires unnecessary manipulation of the tensioning system.
In addition to wheel servicing, both chain and belt equipped drive systems occasionally require servicing and/or replacement of the flexible or endless drive member. Commonly, the endless drive member passes about the crankset and is engaged with the rear sprocket or gear set in a manner such that a chain stay or portion of a frame of the bicycle passes through the endless drive. Said in another way, the crankset is often positioned outboard and the gear set is positioned inboard relative to a drive-side stay assembly. When a chain must be replaced, the user must split the chain by removing a pin from the chain, such as by use of a chain splitting tool, so that two adjacent links of the chain can be disjoined. Although those skilled in the art can become efficient at replacing a chain in the field, provided a replacement chain is on hand, many users are ill-equipped to perform such service in the field, if at all.
Belt based bicycle drive trains present a distinct complication to the servicing of the flexible drive member. Unlike a chain, the endless loop of the belt of the drive train system is not separable. As such, integration of a drive system equipped with a belt with the bicycle requires that portions of the frame that are commonly fixed together be provided in a separable manner.
Others have resolved the issue of passing a frame member through the flexible drive link by rearranging the orientation of the drive system relative to the bicycle. One such solution provides a bicycle assembly wherein the rear wheel gear set is positioned outboard of the drive side chain stay and seat stay assembly. Others provide a cantilevered wheel assembly that is supported by a single fairly robust and substantial seat stay and chain stay assembly. The single seat and chain stay assembly can be positioned between the wheel and the driven member or toward a non-driven side of the wheel assembly. Although such systems improve the serviceability of drive systems equipped with a flexible drive link, such solutions unduly complicate the construction of the bicycle frame and/or detrimentally increase the overall weight of the bicycle.
Accordingly, there is a need for a bicycle wheel support assembly that provides an efficient yet robust system for tensioning a flexible drive member. There is also a need for a bicycle wheel mount assembly that provides independence between mounting of the wheel assembly to the bicycle and adjustment of the flexible member of the bicycle wheel drive system. There is also a need for a bicycle wheel mounting system that can accommodate an inseparable flexible drive in a manner that does not unduly interfere with the overall construction of the bicycle.